Doepfer - A-137-2

Manufacturer Description: Module a-137-2 is another version of a wave multiplier. in contrast to the a-137-1 wavemultiplier the a-137-2 generates four phase-shifted copies of a vco signal applied to the audio input. the four shifted signals are added to the original signal to obtain a fat sound similar to five independent vcos. the phase shifting is made by a simple circuit that works only for sloped signals like sawtooth, triangle or sine, but not for rectangles or pulses. working principle: the audio input signal (typically a sawtooth, triangle or sine wave from a vco) is compared with a slowly varying control voltage (cv shift in). the output of the comparator is a rectangle wave with variable pulsewidth. when the output of the comparatur is added to the input signal (a sawtooth in the example) with the correct level relation between both signals one obtains a phase shifted sawtooth. the left picture shows the incoming sawtooth wave on top. the two horizontal dashed lines (blue and